Photographic color process based on controlled flow of silver ions

ABSTRACT

Positive multicolor images are produced by exposing, developing with a black-and-white developer, washing and then treating with an alkaline processing solution containing a paraphenylene diamine or other color producing developer and minute quantities of silver halide solubilizing agents a film package constructed of emulsion layers backed by color providing layers containing nucleating species and color providing couplers designed to react in said color providing layers with oxidized color developer produced by the catalytic reduction of solubilized silver ions in areas corresponding to unexposed portion of the film package. Between each emulsion and its contiguous nucleating and color providing layer unit is placed a separation layer which impedes the flow of silver ions from one emulsion layer to any layer other than the layer providing color complementary to the sensitized layer. Quantities of silver halide solvent are selected to assure a proper solubilization rate coupled with a rapid physical development effecting a sink condition whereby the nucleating layers pull silver ions of unexposed silver halide grains from adjoining layers only to produce colors complementary to the sensitization of the respective emulsion layers.

United States Patent Waxman et al.

[451 Sept. 2a, 1974 PHOTOGRAPHIC COLOR PROCESS BASED ON CONTROLLED FLOW OF SILVER IONS [75] Inventors: Burton Harvey Waxman, Endwell;

Robert Thomas Shannahan, Endicott; Felix Viro, Apalachin, all of NY.

[73] Assignee: GAF Corporation, New York, NY.

[22] Filed: Aug. 14, 1972 [21] Appl. No.: 280,426

[52] US. Cl 96/22, 96/55, 96/74, 96/109 [51] Int. Cl. G03c 7/16, G03c 1/76, G03c 1/34 [58] Field of Search 96/29 D, 22, 109, 55, 74

[56] References Cited UNITED STATES PATENTS 2,428,054 9/1947 Vittum et al 96/9 2,665,986 1/1954 Rott 96/29 D 2,688,539 9/1954 Heinbach et aI 96/9 3,476,560 1 H1969 Yasuda 96/22 Primary ExaminerRonalcl H. Smith Assistant ExaminerAlfonso T. SuroPico Attorney, Agent, or FirmWalter C. Kehm; Samson B. Leavitt; Martin A. Levitin [5 7] ABSTRACT Positive multicolor images are produced by exposing, developing with a black-and-white developer, washing and then treating with an alkaline processing solution containing a paraphenylene diamine or other color producing developer and minute quantities of silver halide solubilizing agents a film package constructed of emulsion layers backed by color providing layers containing nucleating species and color providing couplers designed to react in said color providing layers with oxidized color developer produced by the catalytic reduction of solubilized silver ions in areas corresponding to unexposed portion of the film package. Between each emulsion and its contiguous nucleating and color providing layer unit is placed a separation layer which impedes the flow of silver ions from one emulsion layer to any layer other than the layer providing color complementary to the sensitized layer. Quantities of silver halide solvent are selected to assure a proper solubilization rate coupled with a rapid physical development effecting a sink condition whereby the nucleating layers pull silver ions of unexposed silver halide grains from adjoining layers only to produce colors complementary to the sensitization of the respective emulsion layers.

24 Claims, 7 Drawing Figures Q) SUPPORT Q2) RED SENS. EMULSION MEMBER REc. LAYER-DEV. NUCLEl-CYAN COLOR FORMER (4) REC. LAYER-DEV. NUCLEI-MDGENTA COLOR FORMER GREEN SENS. EMULSION MEMBER REc. LAYER-DEV. NUCLEl-MAGENTA COLOR FORMER REC. LAYER-DEV. NUCLEI-YELLOW COLOR FORMER BLUE SENS. EMULSION MEMBER THIN SURFACE LAYER A EXPOSED GRAIN A UNEXPOSED GRAIN STEP I EXPOSURE AAAAAAA SILVER HALIDE EMULSION AAAA'AAA ANTIOXIDAN'I' SILVER HALIDE EMULSION 6 WHITE COUPLER ANTIOXIDANT PATENIEUSEPZMSH MEI 1 or (D SUPPORT A A A A A A A @RED SENS. EMULSION MEMEER A A A A A A A I R C-LAYER-DEVNUCLEl-MAGENTA BLUE LIGHT R a D GREEN LIGHT RED LIGHT YELLOW LIGHT CYAN LIGHT 9 WHITE LIGHT- 9 N0 LIGHT F/azA AAVAAEAIAZX- REc. LAYER-DEV. NUCLEI-CYAN COLOR FORMER G) REC. LAYER-DEV. NUCLEl-MAGENTA COLOR FORMER GREEN SENS. EMULSION MEMBER COLOR FORMER REC. LAYER-DEV. NUCLEI-YELLOW COLOR FORMER A EXPOSED GRAIN A UNEXPOSED GRAIN STEP I EXPOSURE SILVER HALIDE EMULSION ANTIOXIDANT SILVER HALIDE EMULSION 8x WHITE COUPLER ANTIOXIDANT PATENIEB 89241914 3.837, 854 mm 2 or. 3

/ STEP 2 saw DEVELOPMENT A DEVELOPED GRAIN A UNDEVELOPED GRAIN STEP 3 PARTIAL SOLUBIL- IZATION OF UNEXPOSED GRAINS AND CHEMICAL POTENTIAL DRAWING GRAINS INTO ADJACENT LAYER A PARTIALLY SOLUBILIZED SILVER HALIDE GRAINS PI- IOTOGRAPHIC COLOR PROCESS BASED ON CONTROLLED FLOW OF STLVER IONS This invention relates to an intranegative silver ion transfer method which provides a positive reproduction of an original scene as regards true hue, saturation and density variation with minimized granularity.

The silver ion diffusion or silver stream system is best known as the process upon which the black-andwhite Polaroid film is based. The silver stream requires reduction of exposed silver halide and solubilization of unexposed silver halide grains in the negative portion of the package with a simultaneous migration of the solubilized species to a receiving layer where incorporated nuclei catalyze reduction, and the formation of a positive image.

Subsequent to the commercial realization of the black-and-white Polaroid product, several attempts were made to accommodate the silver stream process with those of normal or instant access color films. Our invention relates to the former attempted accommodation.

Muessen et al., US. Pat. No. 2,673,800 illustrates diffusion fast cyan, magenta, and yellow color formers in separation layers adjacent to the red, green and blue light sensitive silver halide emulsion layers respectively, these coupling with oxidized developer to provide the subtractive colors necessary for multicolor reproductions.

Various patents have claimed utilization of the silver stream process to provide multilayer color products re- -quiring multistep processing, resulting in films of greater speed and reduced grain, as well as new and improved instant access color systems.

See Bloom, et al., US. Pat. Nos. 3,439,548, 3,443,939 and 3,443,940 and Rogers, US. Pat. Nos. 3,443,941 and 3,443,943.

In each of these schemes, image formation is predicated on a rapid solubilization of undeveloped silver halide grains and a reduction of these grains within those layers or in adjacent layers to provide color products (or metallic silver alone, as in the case of the Dye- Bleach System).

As a catalyst for the reduction of the complexed silver ions, metallic nuclei, or metallic sulfides have been suggested. The effectiveness of these catalysts is dependent on their concentration and the thickness of the layers in which they are contained. Barrier layers containing metallic nuclei, sulfides, complexing agents, etc., have also been described in order to control the flow of errant silver ions and retard color contamination.

The systems described in these patents, while adequate for monolayer packages, fail to be effective in multilayer films. The rate of solubilization of the silver halide grains is too rapid to control their direction and extent of flow, making color separation difficult, if not impossible. Furthermore, the lack of control caused by this rapid solubilization and the problems involved (as evidenced by the need for barrier layers) results in an inefficient use of non-exposed silver halide grains.

Our invention employs silver halide solvent concentrations incapable of causing sufficient solubilization by themselves and would fail to initiate the mechanisms of the prior art. A better understanding of our invention is to be had by considering the following.

One could not predict beforehand that small concentrations of a silver halide solvent such as thiosulfate (below 10 grams/liter, but preferably below 2 grams/- liter), would suffice to solubilize silver halide at a significant rate for silver ion transfer out of a silver halide containing layer. It has been unexpectedly found that when an immediately adjacent (0 to 1.0 micron distant) layer contains a reaction-providing species for that silver ion, such as nuclei for silver reduction, that concentration of silver solvent now suffices for a significant mass transfer of silver ions between that layer and the reaction-providing layer.

It has been further found that this effect falls off sharply with distance, such that when the reactionproviding layer is more remote (3 to 6 microns distant) that critically small concentration of silver solvent once more acts as expected, that is to say it does not provide sufficient solubilization for significant transfer of silver ions from the silver-providing layer to that more distant reaction-providing layer.

This can be best understood by appeal to the thermodynamic concept of chemical potential which is to entropic force fields what electromotive force is to electric force fields; just as mass transfer (i.e., silver ion transfer) is to entropic force fields what current or electron movement is to electric force fields.

It is now apparent that the critically small concentration of silver solvent employed does not create by itself a concentration gradient profile sufficient to set up a chemical potential between adjacent layers large enough for significant transfer of silver ions from one layer to another. It is now apparent that the reactionproviding layer itself cannot, by virtue of its capacity as a sink for silver ions, generate a concentration profile gradient sufficient to set up a chemical. potential between adjacent layers large enough for significant silver ion transfer; but that the sum of their capacities does sufiice to generate a concentration profile gradient between adjacent layers large enough for significant silver ion transfer. It is also now apparent that even their summed capacities for initiating silver ion transfer between silver source and silver reacting layers more remote (3 to 6 microns distant) does not suffice for significant silver ion transfer.

The above thermodynamic argument details the difference between solvent induced silver ion transfer in prior art systems and reaction aided silver ion transfer in these systems. The former is characterized by high silver halide solvent concentrations, sufficient to move silver halide throughout the system with no bearing on the intended reaction site, leading to ghost images. The latter is characterized by sufficiently low solvent concentrations to afford the sink potential of the reaction site to play a significant role in the mass transfer of silver ions, the nearby reaction sites having a distinctively larger effect than those more remote. This mode of intranegative transfer allows for design to limit silver ion transfer to desired intranegative transfers without the acceptance of undesirable intranegative transfers as a penalty.

Although we now recognize these two modes of transfer, the dividing line between the two was crossed as a result of happy and accidental discovery. This cross-over line must be found by experimental variations in concentration and distance parameters for the systems involved, such experiments to be detailed below.

In general, the parameters defining the reactionaided transfer mode for a given system and silver solvent are not independent of each other, and such mode of transfer is not a function of any one of them. Thus, for example, while a low silver solvent concentration of 2 grams/liter might be characteristic of the low levels employed in our invention, a too thin dividing layer between the silver source and an unwanted reaction site might have the effect of triggering an unwanted transfer.

Thus, for example, if a spacing layer of from 3 to 6 microns in our invention is combined with too high a silver solvent concentration, the unwanted mode of transfer is activated even though the distance parameter is within the scope of our invention.

In usual practice, the distance parameter is set, and a silver concentration is found which lies below the dividing line between these two modes of transfer. This value will, of course, be different for different silver solvents.

It is among the teachings of our invention that when the photosensitive package is coated, using the above learned distance parameters, and the critically small concentration of silver solvent is not exceeded, that the intranegative transfers will be limited to the following three, without complicated means being required to bar other undesirable intranegative transfers: the undeveloped silver halide from the blue record will transfer specifically and solely to the adjacent reactionproviding layer affording a positive yellow image therein; and the undeveloped silver halide from the green record will transfer specifically and solely to the adjacent reaction-providing layer affording a positive magenta image therein; and the undeveloped silver halide from the red record will transfer specifically and solely to the adjacent reaction-providing layer affording a positive cyan image therein. The net effect of the three operative intranegative silver transfers only is a composite dye image yielding a true rendering of the variations in hue, saturation and density of the original scene.

Whereas the prior literature suggests 2.5 to grams/liter of sodium thiosulfate in the processing solution, applicants have discovered that quantities of be tween 0.1 to 0.5 grams/liter of this same salt is most effective in realizing a multicolor silver stream process of high color saturation and excellent color integrity. Substitution of sodium thiocyanate (a much weaker solubilizing species than the sodium thiosulfate analog) requires between 0.5 to 2.0 grams/liter for optimization.

The above results were observed with medium speed bromoiodide emulsions currently used in camera speed films of the color print type.

Once more, while it is true that the range of 0. l to 0.5 grams/liter of sodium thiosulfate may be specific for a given emulsion, it is an essential point of the present invention that for any given emulsion the rate of solubilization of the unexposed silver halide grains must be dependent on the nucleating ability of the adjacent layers to catalyze their reduction. If, for example, the emulsion tested is coated with a gel separation layer between it and the nucleating layer, it should be found, assuming the proper amount of thiosulfate salt is used, that decreasing rates of solubilization and hence, color formation, is observed when the gel separation is increased from zero to 5.0 microns dry thickness. With a 5.0 microns thick separation layer, little or no nucleation should occur during the time that complete color saturation would occur in the samples without separation layers.

In order to more clearly describe the invention. reference is made to the drawings.

FIG. 1 represents a package by which the practice of our invention may lead to a positive three color reproduction of the original scene. The figure shows the package during the exposure stpe.

FIG. 2A shows in detail the photosensitive member 2, 5, and/or 8 of FIG. I in one embodiment of our invention.

FIG. 2B shows in detail the photosensitive member 2, 5, and/or 8 of FIG. I in a second embodiment of our invention.

FIG. 3 shows the package in FIG. 1, as practiced in the first embodiment, after black and white development and prior to color development.

FIG. 4 shows the package in FIG. 1, as practiced in the first embodiment, during the intranegative transfers of silver ions. The arrows indicate only the intranegative transfers allowed by the proper practice of our invention.

FIG. 5 shows the package in FIG. 1, as practiced in either embodiment, after the bleach and fix step.

FIG. 6 shows the structure of some color formers useful in the practice of the invention. I, II and III are typical of those used in either embodiment and IV is typical of the white coupler, the concept of which will be de scribed later, useful to the second embodiment.

For the practice of the first embodiment reference is made to FIG. I and to FIG. 2A which represent in detail the structure of silver halide members 2, 5, and 8 from FIG. 1 in this first embodiment, namely a single layer, 10, of silver halide emulsion sensitized to the red portion of the spectrum when representative of 2; the green portion of the spectrum when representative of 5; and limited to its inherent natural blue sensitivity when representative of 8.

The photosensitive package for the first embodiment is coated as shown in FIG. 1 on layer 1, which is a support base and can be either a film base such as polyester or thermoplastic cellulose film base material or baryta coated paper or polyethylene-laminated-paper base, which base is prepared for the silver halide gelatin or colloid coating by a surface preparation known in the art as subbing.

Layer 2 is an element described by FIG. 2A as explained above for this embodiment and serves as the red recording layer.

Layer 3 is a gelatin or gelatin substitute matrix containing development nuclei such as colloidal particles of noble metal or noble metal sulfides, but preferably, a colloidal dispersion of silver metal particles of a size such that they may act as a yellow filter during exposure and as development nuclei promoting color physical development in the presence of unreduced silver ions representing the positive record of, and coming from the immediately adjacent silver halide layer. This layer also contains a cyan forming non-diffusible color former, such as, but not limited to, color former I in FIG. 6.

Layer 4 plays the color providing role for layer 5, just as layer 3 does for layer 2 and is so constituted as layer 3 except that in place of a cyan providing color former, a non-diffusible magenta providing color former is included such as, but not limited to, color former II in FIG. 6. This layer is of 3 to 6 microns thickness so as to provide, co-jointly with its operation as a color providing layer, the spacing requirements between the independently acting color providing elments learned from the above explained teachings of our invention.

This co-joint feature is not a requirement of our invention and layer 4 or layer 6, but not both, may be replaced with an inert gelatin layer of 3-6 microns thickness leaving the operation of the invention intact.

The preferred embodiment, as indicated, does serve to maximize the color response of the green record, which color is most important to the impressions made on the human retina by the composite dye image, so that the co-joint action of layers 4 and 6, said layers being identically constituted, is preferable tothe replacement of any one of them by an inert gelatin layer of 3-6 microns thickness.

Layer 5 is an element as described before for FIG. 2A for this embodiment and serves as the green recording layer.

Layer 6 is identical and equal in role to layer 4.

Layer 7 plays the color providing role for layer 8, just as the other color providing layers act only with their companion silver halide layers, and is so constituted, except insofar as it contains a non-diffusible yellow forming color former such as, but not limited to, color former III in FIG. 6.

Layer 8 is an element as described before by FIG. 2A for this embodiment and serves as the blue recording layer.

Layer 9 is a thin layer of hardened gelatin which serves to protect both the unexposed photosensitive package and the fully processed positive color reproduction against abrasive action. This layer may also contain one of many U.V. absorbers well known to the art.

FIG. 1 in addition to describing the several strata of the photosensitive package of the first embodiment (along with FIG. 2A) shows the action of light in registering the color of incident light by providing developable latent image in the proper layer of the exposed area.

In this first embodiment the exposed photosensitive package is first developed in any black and white developer or combination of these developers, converting the light struck silver as shown in FIG. 1 into metallic silver as shown in FIG. 3. This, in effect, removes such light struck silver halide from playing a role in the next step, and provides a positive record of the exposure action in terms of undeveloped silver halide.

The next step in this first embodiment consists of a physical development in an alkaline processing solution containing at least a p-phenylene diamine type color developer and a silver halide solvent such as thiosulfate in aconcentration of below 10 grams/liter but preferably below 2 grams/liter, but especially at that critical concentration which by experiment, as described heretofore, provides only reaction aided silver ion transfer when used in combination with the distance parameters inserted into the package in the thicknesses of layers 4 and 6.

Since no further exposure occurs between the black and white negative development and this physical color development, the reaction with this color developer is not one of the development of the non-latent-image bearing silver halide grains left over from the first development but rather a solubilization in part, in cooperation with the physical development thereof in adjacent color providing layers only, and transport of that left-over silver halide to said adjacent layers, only, to ultimately provide, via oxidative coupling with the pphenylene diamine oxidation product from such physical development of silver ions on to pre-existing development nuclei, a permanent non-diffusible dye record of that positive silver halide record from non-diffusible color former adjacent only to those areas in the silver halide record layer not exposed to light and not in the silver halide layer itself as in more conventional reversal films.

This has the advantage of superimposing not the granularity of the silver halide recording emulsion on the final dye record, but rather the granularity pattern resulting from the colloidal dispersion of the development nuclei; allowing one criteria of choice of colloidal dispersion to be its granularity characteristics, eliminating such effect from the choice of a silver halide emulsion. In contrast to more conventional reversal films, emulsion choices may be made for speed with less critical note being taken of the speed to grain penalty well known to the art.

Furthermore, in our invention such advantage as above may be taken (inherent in any intranegative silver ion transfer scheme), avoiding the new penalty of color contamination, due to the tight restriction of silver ion transport between only those layers recording a particular hue, and those adjacent layers affording a color providing reaction yielding only that hue complementary to the recorded hue. FIG. 4 shows by arrows the only intranegative transports allowed in reaction aided silver ion diffusion.

FIG. 5 shows the fully developed photosensitive package after shortstop, bleach, fix and wash or stabilizing baths deemed necessary for the system involved rendering a true positive color reproduction of the original scene as regards hue, saturation, and density variations.

In the second embodiment the single layer emulsion elements 2, 5 and 8 as in FIG. l, are actually composed of 3 layers each as in FIG. 2B; 10 representing the silver halide emulsion layer containing also a white coupler to be described below, and in which the silver halide is sensitized to red light when FIG. 28 represents layer 2; is sensitized to green light when FIG. 28 represents layer 5; and is sensitive to blue light when FIG. 2B represents layer 8 in FIG. I.

In FIG. 2B, layer 10 is flanked on both sides by thin gelatin layers (11) and (12), (less than 1.0 microns) containing well known hydroquinone derivatives which are commonly used as scavengers to react with any oxidized p-phenylene diamine developer seeking to leave layer 10.

All other aspects of the second embodiment are as in FIG. 1.

In this second embodiment the exposed photosensitive package is subjected to but one alkaline processing solution containing at least a p-phenylene diamine type developer and a silver halide solvent at that concentration critical to the promotion of reaction aided silver ion diffusion.

The negative image development of light struck silver halide by the p-phenylene diamine type developer occurs simultaneously with the transport of non-latent image bearing silver halide, in part due to solubilization, in part due to reaction providing adjacent sinks, as in the first embodiment, to provide the same final result shown in FIG. 5 after shortstop, bleach, fix and wash steps.

In this embodiment oxidized p-phenylene diamine is produced in emulsion members 2, 5 and 8 which must be scavenged and not allowed to leave said members.

In part this scavenging step is provided by the flanking layers 11 and 12 in FIG. 2B.

In greater part, this scavenging step is provided by reaction of this unwanted oxidized developer with socalled white couplers.

White couplers, which are well known in the art (see, for example, On The Chemistry of White Couplers by W. Puschel, Mitt. Forshunglab. AGFA Leverkusen- Muenchen 4, 352-67 (1964) reaction with oxidized p-phenylene diamine to yield colorless substances thought to be stable leuco dyes. A white coupler such as, but not limited to, color former IV in FIG. 6 is useful in this embodiment.

This second embodiment embraces all the advantages of the first embodiment plus the further advantage of requiring but a single developer bath to yield a positive dye record.

Below are some examples demonstrating the practice of our invention. These are to be taken illustrative only and the practice of our invention is not limited to these examples.

EXAMPLE I A photosensitive element comprised of the following layers is coated:

1. Support 2. A bromoiodo photographic emulsion with a silver coating weight of 1.0 grams/square meter.

3. A gelatin matrix containing Carey-Lea silver and the non-diffusible cyan forming color former shown as I in FIG. 6 (or any other non-diffusible cyan forming color former including those so-called lipophilic color formers well known to the art which may be in cluded in coated layers as dispersions in a high boiling organic solvent). This color former is coated to a coating weight of 0.5 grams/square meter. The Carey-Lea silver is coated to a weight of 0.05 grams/square meter.

DEVELOPER l;

5 grams Metol 0.l grams Phenidone B 0.] grams Sodium thiosulfate 2 grams Sodium sulfite 4 grams KOH 2 l .0 grams I-Iydroxylamine sulfate 2 0 grams Boric acid 18.0 grams NaCl 2.5 grams Benzyl alcohol 2.0 ml. *Alipal CO 436 0.83 ml Trade name for the ammonium salt of a sulfated nonylphenoxy poly (ethylene oxy) ethanol. sold by GAF Corp.

Following this treatment, the element was shortstopped, bleached, fixed, washed and dried. Inspection showed a cyan colored positive reproduction of the original wedge.

EXAMPLE II A photosensitive element comprised of the following layer is coated:

l. A support 2. Identical to layer 2 in Example I 3. An inert gelatin layer 5.0 microns in thickness 4. A layer identical to layer 3 in Example I.

The photosensitive element is exposed and processed as in Example I. Inspection showed a blank piece of film with no cyan positive reproduction of the original wedge as in Example I. Examination of an unbleached element, subjected to all the other steps, showed a silver negative reproduction of the wedge, indicating that the Liquadol was operative but the developer 1 was not operative between the silver ion source (layer 2) and a color providing layer some 5.0 microns away in this example (layer 4).

EXAMPLE III The photosensitive element in Example II is exposed, developed in Liquadol, followed by a treatment in developer 2 which has the same composition as developer 1, except insofar as the concentration of sodium thiosulfate is increased from 0.5 grams/liter to 3.0 grams/- liter. The element is then shortstopped, bleached, fixed, washed and dried. Inspection of the dried element shows a cyan colored positive reproduction of the original wedge, indicating that a silver transport mechanism has become operative at this higher silver solvent concentration across the 5.0 micron spacing layer.

EXAMPLE IV A multicolor photosensitive element is coated as follows:

l. A support 2. A bromoiodo emulsion layer as in layer 2, Example 1, except insofar as it is sensitized to red light by any sensitizing dye known to the art.

3. A gelatin matrix layer identical to layer 3, Example I.

4. An inert gelatin layer 5.0 microns in thickness.

5. A gelatin matrix layer identical to layer 3, Example I except insofar as it contains the yellow color forming color former, III, FIG. 6 (or any other non-diffusible yellow forming color former including those so-called lipophilic" color formers well known to the art which may be included in coated layers as dispersions in a high boiling organic solvent).

6. An unsensitized bromoiodo emulsion layer having inherent blue light sensitivity identical to layer 2, Example I.

The element is exposed to actinic radiation through a target containing blue patches and red patches, developed in Liquadol, then treated with no further exposure to light with developer 1 of Example I, shortstopped, bleached, fixed and washed. Inspection of the dried element showed pure yellow image in those areas exposed to red patches and pure cyan image in those areas exposed to blue patches indicating that a silver transport mechanism was operative between layers 2 and 3; and layers 6 and 5; but inoperative between layers 2 and 5; and layers 6 and 3.

EXAMPLE V A multicolor photosensitive element of Example IV is exposed and treated as it was in Example IV, except insofar as the higher silver solvent developer 2 is substituted for developer 1. Inspection of the dried element showed yellow image tainted with cyan in those areas exposed to the red patches, and cyan image tainted with yellow in those areas exposed to the blue patches, indicating that all possible silver transport mechanisms are operating at this level, wanted and unwanted; that is to say, silver transport mechanisms between layers 2 and 3; layers 2 and layers 6 and 5; and between layers 6 and 3.

EXAMPLE VI A three color photosensitive package embracing the first embodiment is coated as follows:

1. A support 2. A bromoiodo emulsion layer identical to layer 2, Example IV which serves as the red record.

3. A gelatin matrix layer identical to layer 3, Example I which serves as the cyan color forming layer.

4. A gelatin matrix layer identical in composition to layer 3, except insofar as it contains enough gelatin to coat at 5.0 microns dry thickness and except insofar also as it contains in place of a cyan color forming color former, the non-diffusible magenta color former ll, FIG. 6 (or any other non-diffusible magenta forming color former known to the art including those so-called lipophilic color formers which may be included in a layer as a dispersion in high boiling organic solvent). This layer serves co-jointly as a magenta color providing layer and to maintain the spacing requirements learned from the other examples.

5. A bromoiodo emulsion identical to layer 2, except insofar as it is sensitized to green light and serves as the green record.

6. Another magenta providing layer identical to layer 4 in composition, structure, and role (optionally layer 6 or layer 4, but not both, may be identical to layer 4, Example IV without obviating the intent of the invention).

7. A layer identical to layer 5 of Example [V which serves as the yellow color providing layer.

8. A layer identical to layer 2 of Example I which serves as the blue record layer.

9. A thin coating of inert gelatin serving as protection for the photosensitive package.

The photosensitive package is exposed to actinic radiation through a target containing red, green, blue, cyan, magenta, and yellow patches plus a neutral density photographic wedge. The so exposed package is developed first in Liquadol developer and thereafter with no further exposure to light is treated in developer 1 of Example I. It is then shortstopped, bleached, fixed, washed and dried. Inspection of the dried package shows a fine grained positive color reproduction of the original target with no color contamination.

EXAMPLE VII A three color photosensitive package embracing the second embodiment is coated as follows:

1. A support 2. A bromoiodo emulsion layer as in layer 2 of Example 6 except insofar as it also includes the white coupler IV, FIG. 6 (or any other colorless coupler known to the art) and which serves as the red record.

3. A thin (less than 1.0 micron) gelatin layer containing 2,5-ditertiary amyl hydroquinone as an antioxidant.

4. A layer identical to layer 3 of Example Vl which serves as the cyan color providing layer.

5. A layer identical to layer 4 of Example VI which serves as a magenta color providing layer and as a spacing layer to realize the teachings of our intention.

6. Another scavenger layer identical to layer 3, this example.

7. A bromoiodo emulsion layer identical to layer 2, this example, except insofar as it is sensitized to green light and serves as the green record.

8. Another scavenger layer identical to layer 3, this example.

9. Another magenta color providing layer identical in content and structure to layer 5, this example.

10. A yellow color providing layer identical to layer 5 of Example IV.

1 I. Another scavenger layer identical to layer 3, this example.

12. A bromoido emulsion layer identical to layer 2, this example, except insofar as it is sensitive to blue light only and serves as the blue record.

13. A surface layer of inert gelatin.

The photosensitive package is exposed to actinic radiation through a target containing red, green, blue, cyan, magenta and yellow patches plus a neutral density sensitometric wedge. The so exposed package is developed but once, in developer 1, shortstopped, bleached, fixed, washed and dried. Inspection of the dried package shows a fine grained positive color reproduction of the original target with no color contamination.

This invention has been disclosed with respect to certain preferred embodiments, and it will be understood that various modifications and variations will become obvious to persons skilled in the art and are to be included within the spirit and purview of this application and the scope of the appended claims.

What we claim is:

l. A photographic element for producing positive multi-color images by exposure, development and treatment with an alkaline processing solution containing a silver halide solvent and a p-phenylenediamine color developer, comprising a support, at least two light-sensitive silver halide emulsion layers carried by said support, each said emulsion layer being sensitized to a different primary color, and a nucleating layer adjacent to and associated with each said emulsion layer, each said nucleating layer comprising (a) a colorless non-diffusible color former capable of forming a color complementary to said primary color of said associated emulsion layer by coupling with the oxidation product of a p-phenylenediamine color developer, and (b) development nuclei for catalyzing the reduction of silver halide transferred into said nucleating layer, the distances between each said emulsion layer and the nucleating layers in the photographic element being a function of the silver halide solvent concentration in the alkaline processing solution used in subsequent treatment of the element, said distances being effective, with respect to a given silver halide solvent concentration, to limit transfer of silver halide from each said emulsion layer to only its associated nucleating layer,

and each nucleating layer is less than 3 microns away from its associated emulsion layer and at least 3 microns away from other emulsion layers.

2. The photographic element according to claim 1, wherein each nucleating layer is located to 1.0 micron away from its associated emulsion layer.

3. The photographic element according to claim 1, wherein each nucleating layer is 3-6 microns away from said other emulsion layers.

4. The photographic element according to claim 1, wherein three silver halide emulsion layers are provided, sensitized to red, green and blue, respectively.

5. A photographic element for producing positive multi-color images by exposure and development with an alkaline processing solution containing a silver halide solvent and a p-phenylenediamine color developer, comprising a support; at least two light-sensitive silver halide emulsion layers carried by said support, each said emulsion layer being sensitized to a different primary color; a nucleating layer adjacent to and associated with each said emulsion layer, each said nucleating layer comprising (a) a colorless non-diffusible color former capable of forming a color complementary to said primary color of said associated emulsion layer by coupling with the oxidation product of a pphenylenediamine color developer, and (b) development nuclei for catalyzing the reduction of silver halide transferred into said nucleating layer, the distances between each said emulsion layer and the nucleating layers in the photographic element being a function of the silver halide solvent concentration in the alkaline processing solution used in subsequent treatment of the element, said distances being effective, with respect to a given silver halide solvent concentration, to limit transfer of silver halide from each said emulsion layer to only its associated nucleating layer, and each nucleating layer is less than 3 microns away from its associated emulsion layer and at least 3 microns away from other emulsion layers; and chemical means for scavenging oxidized p-phenylenediamine produced during development.

6. The photographic element according to claim 5, wherein said scavenging means is provided by a white coupler in each said silver halide emulsion layer.

7. The photographic element according to claim 6, wherein said scavenging means further includes a white coupler or anti-oxidant incorporated in a scavenging layer, and a said scavenging layer is interposed directly between each said emulsion layer and any other layer.

8. The photographic element according to claim 5, wherein each nucleating layer is located 0 to 1.0 micron away from its associated emulsion layer.

9. The photographic element according to claim 5, wherein each nucleating layer is 3-6 microns away from said other emulsion layers.

10. The photographic element according to claim 5, wherein three silver halide emulsion layers are provided, sensitized to red, green and blue, respectively.

11. A process for producing positive multi-color images from the photographic element of claim 1, said photographic element having been imagewise exposed to actinic radiation, which comprises developing said element with a black and white developer to convert light exposed silver halide to metallic silver and thereby form a negative, and physically developing said negative with an alkaline processing solution comprising a p-phenylenediamine color developer and a silver halide solvent, the concentration of said silver halide solvent being not more than 2 grams per liter and effective, in combination with the relative distances between the emulsion layers and the nucleating layers, to transport unexposed silver halide from an emulsion layer to only its associated nucleating layer, whereby said transported unexposed silver halide is catalytically reduced by said p-phenylenediamine color developer and said colorless color former couples with the oxidation product of the p-phenylenediamine color developer to form positive color images in said nucleating layers.

12. The process according to claim 11, wherein the silver halide solvent is sodium thiosulfate and the concentration thereof is 0.1 to 0.5 grams per liter.

13. The process according to claim 11, wherein the silver halide solvent is sodium thiocyanate and the concentration thereof is 0.5 to 2.0 grams/liter.

14. The process according to claim 11, wherein each nucleating layer is located 0 to 1.0 micron away from its associated emulsion layer.

15. The process according to claim 11, wherein each nucleating layer is 3-6 microns away from said other emulsion layers.

16. The process according to claim 1 1, wherein three silver halide emulsion layers are provided. sensitized to red, green and blue, respectively.

17. A process for producing positive multi-color images from the photographic element of claim 11, said photographic element having been imagewise exposed to actinic radiation, which comprises directly forming said positive multicolor images by treating said element with an alkaline processing solution comprising a pphenylenediamine color developer and a silver halide solvent, the concentration of said silver halide solvent being not more than 2 grams per liter and effective, in combination with the relative distances between the emulsion layers and the nucleating layers, to transport unexposed silver halide from an emulsion layer to only its associated nucleating layer, whereby said transported unexposed silver halide is catalytically reduced by said p-phenylenediamine color developer and said colorless color former couples with the oxidation product of the p-phenylenediamine color developer to form positive color images in said nucleating layers.

18. The process according to claim 17, wherein the silver halide solvent is sodium thiosulfate and the concentration thereof is 0.1 to 0.5 grams per liter.

19. The process according to claim 17, wherein the silver halide solvent is sodium thiocyanate and the concentration thereof is 0.5 to 2.0 grams/liter.

20. The process according to claim 17, wherein said scavenging means is provided by a white coupler in each said silver halide emulsion layer.

21. The process according to claim 20, wherein said scavenging means further includes a white coupler or anti-oxidant incorporated in a scavenging layer, and a said scavenging layer is interposed directly between each said emulsion layer and any other layer.

22. The process according to claim 17, wherein each nucleating layer is located 0 to 1.0 micron away from its associated emulsion layer.

23. The process according to claim 17, wherein each nucleating layer is 3-6 microns away from said other emulsion layers.

24. The process according to claim 17, wherein three silver halide emulsion layers are provided, sensitized to red, green and blue, respectively. 

2. The photographic element according to claim 1, wherein each nucleating layer is located 0 to 1.0 micron away from its associated emulsion layer.
 3. The photographic element according to claim 1, wherein each nucleating layer is 3-6 microns away from said other emulsion layers.
 4. The photographic element according to claim 1, wherein three silver halide emulsion layers are provided, sensitized to red, green and blue, respectively.
 5. A photographic element for producing positive multi-color images by exposure and development with an alkaline processing solution containing a silver halide solvent and a p-phenylenediamine color developer, comprising a support; at least two light-sensitive silver halide emulsion layers carried by said support, each said emulsion layer being sensitiZed to a different primary color; a nucleating layer adjacent to and associated with each said emulsion layer, each said nucleating layer comprising (a) a colorless non-diffusible color former capable of forming a color complementary to said primary color of said associated emulsion layer by coupling with the oxidation product of a p-phenylenediamine color developer, and (b) development nuclei for catalyzing the reduction of silver halide transferred into said nucleating layer, the distances between each said emulsion layer and the nucleating layers in the photographic element being a function of the silver halide solvent concentration in the alkaline processing solution used in subsequent treatment of the element, said distances being effective, with respect to a given silver halide solvent concentration, to limit transfer of silver halide from each said emulsion layer to only its associated nucleating layer, and each nucleating layer is less than 3 microns away from its associated emulsion layer and at least 3 microns away from other emulsion layers; and chemical means for scavenging oxidized p-phenylenediamine produced during development.
 6. The photographic element according to claim 5, wherein said scavenging means is provided by a white coupler in each said silver halide emulsion layer.
 7. The photographic element according to claim 6, wherein said scavenging means further includes a white coupler or anti-oxidant incorporated in a scavenging layer, and a said scavenging layer is interposed directly between each said emulsion layer and any other layer.
 8. The photographic element according to claim 5, wherein each nucleating layer is located 0 to 1.0 micron away from its associated emulsion layer.
 9. The photographic element according to claim 5, wherein each nucleating layer is 3-6 microns away from said other emulsion layers.
 10. The photographic element according to claim 5, wherein three silver halide emulsion layers are provided, sensitized to red, green and blue, respectively.
 11. A process for producing positive multi-color images from the photographic element of claim 1, said photographic element having been imagewise exposed to actinic radiation, which comprises developing said element with a black and white developer to convert light exposed silver halide to metallic silver and thereby form a negative, and physically developing said negative with an alkaline processing solution comprising a p-phenylenediamine color developer and a silver halide solvent, the concentration of said silver halide solvent being not more than 2 grams per liter and effective, in combination with the relative distances between the emulsion layers and the nucleating layers, to transport unexposed silver halide from an emulsion layer to only its associated nucleating layer, whereby said transported unexposed silver halide is catalytically reduced by said p-phenylenediamine color developer and said colorless color former couples with the oxidation product of the p-phenylenediamine color developer to form positive color images in said nucleating layers.
 12. The process according to claim 11, wherein the silver halide solvent is sodium thiosulfate and the concentration thereof is 0.1 to 0.5 grams per liter.
 13. The process according to claim 11, wherein the silver halide solvent is sodium thiocyanate and the concentration thereof is 0.5 to 2.0 grams/liter.
 14. The process according to claim 11, wherein each nucleating layer is located 0 to 1.0 micron away from its associated emulsion layer.
 15. The process according to claim 11, wherein each nucleating layer is 3-6 microns away from said other emulsion layers.
 16. The process according to claim 11, wherein three silver halide emulsion layers are provided, sensitized to red, green and blue, respectively.
 17. A process for producing positive multi-color images from the photographic element of claim 11, said photographic element hAving been imagewise exposed to actinic radiation, which comprises directly forming said positive multicolor images by treating said element with an alkaline processing solution comprising a p-phenylenediamine color developer and a silver halide solvent, the concentration of said silver halide solvent being not more than 2 grams per liter and effective, in combination with the relative distances between the emulsion layers and the nucleating layers, to transport unexposed silver halide from an emulsion layer to only its associated nucleating layer, whereby said transported unexposed silver halide is catalytically reduced by said p-phenylenediamine color developer and said colorless color former couples with the oxidation product of the p-phenylenediamine color developer to form positive color images in said nucleating layers.
 18. The process according to claim 17, wherein the silver halide solvent is sodium thiosulfate and the concentration thereof is 0.1 to 0.5 grams per liter.
 19. The process according to claim 17, wherein the silver halide solvent is sodium thiocyanate and the concentration thereof is 0.5 to 2.0 grams/liter.
 20. The process according to claim 17, wherein said scavenging means is provided by a white coupler in each said silver halide emulsion layer.
 21. The process according to claim 20, wherein said scavenging means further includes a white coupler or anti-oxidant incorporated in a scavenging layer, and a said scavenging layer is interposed directly between each said emulsion layer and any other layer.
 22. The process according to claim 17, wherein each nucleating layer is located 0 to 1.0 micron away from its associated emulsion layer.
 23. The process according to claim 17, wherein each nucleating layer is 3-6 microns away from said other emulsion layers.
 24. The process according to claim 17, wherein three silver halide emulsion layers are provided, sensitized to red, green and blue, respectively. 